welding Spider Gears - open Differential Components - Photo 10910896

The basic "open" differential is comprised of a carrier, four spider gears, thrust washers, a center pin, and a lock pin. The two larger spider gears are splined for your rig's axleshafts to slide through and allow them to rotate at different speeds when uneven force is encountered by the tires. This makes it to where power travels down the path of least resistance. For example, if you had one tire planted on a rock and the other in the air, all the power would be sent to the tire in the air.